This invention relates to rotary irrigation sprinklers and specifically, to a stream deflector that limits the distribution of a stream emitted by the sprinkler spray plate to less than the 360-degree circle pattern that would otherwise be irrigated by the stream.
In agricultural irrigation systems, rotary-type sprinklers are used to irrigate large areas of land; and for much of the interior portions of the field to be irrigated, a full 360-degree circular pattern is used with good results. There are instances, however, where one or more sprinklers are located close to the edge of the field, for example, along a roadway, where it is desired to limit the normal 360-degree (or full-circle) pattern of the one or more sprinklers to avoid undesirable and wasteful watering of the roadway (or other structure(s) along the edge of the field).
There are, of course, mechanically and/or electrically reversible sprinklers with adjustable stops to achieve a desired arcuate pattern, less than full circle. In addition, simple “road guards” or other stream deflectors have been employed to inhibit a full-circle pattern by deflecting the stream emitted by the sprinkler spray plate back onto the field within a limited portion of the rotation of the spray plate. In one example, the deflector is attached to a rotary sprinkler, and includes a substantially semi-circular, generally concave shell formed with grooves on its interior (concave) surface that receive and redirect the stream back towards the area just watered, thus protecting the area behind the sprinkler from the emitted stream (see U.S. Pat. No. 4,191,331).
A problem associated with deflectors similar to that described in the '331 patent is that the redirected stream is not uniformly distributed over the remaining pattern area exposed to the stream. By way of example, if the full-circle, normal pattern area is to be reduced to a half-circle pattern, a uniformity problem arises that is related to the groove configuration on the deflector. As will be explained further herein in connection with FIG. 14, the deflector grooves lie on a radius drawn on or near an imaginary center of the arcuate deflector (that may correspond to the sprinkler spray plate axis), and the grooves are substantially straight in a radial direction from their inlet ends, through the concave portion of the deflector shell, to their outlet ends. As a result, a stream entering the inlet side edge of the deflector, to the left of center as the nozzle rotates, is redirected generally toward the outlet side of the deflector, but the outlet stream traces a line angled away from the outlet side edge of the deflector. Similarly, as the stream moves across and within the deflector grooves, eventually impinging on the last groove on the outlet side of the deflector, the stream is redirected back toward the inlet side but, again, tracing a line angled away from the inlet side edge of the deflector. As a result, there are angled or wedge-shaped gaps extending from opposite sides of the deflector that do not receive redirected water, while the center area between these two gaps, is watered by the redirected stream, resulting in an unacceptable lack of uniformity across the area directly in front of the sprinkler/deflector.
There remains a need therefore, for a simple, easy-to-install, and inexpensive road guard or deflector that substantially eliminates or at least minimizes the nonuniformity issue associated with prior road guards or deflectors.